Continuous field amplification-liquid-liquid electric extraction device and application thereof

Abstract

The invention relates to a continuous field amplification-liquid-liquid electric extraction device and application thereof, and relates to the technical field of chemical analysis. The device comprises an extraction assembly which comprises an electrolyte supplementing device, a flushing device and an electrolyte electrode wire, the electrolyte supplementing device is used for containing an electrolyte solution, the flushing device is used for containing flushing liquid, one end of the electrolyte electrode wire is used for being immersed in the electrolyte solution, and the other end of the electrolyte electrode wire is used for being grounded; the sample assembly comprises a sample container, a receiving tube and a sample electrode wire, the sample container is used for containing a to-be-extracted object, one end of the receiving tube is used for immersing the to-be-extracted object, and the other end of the receiving tube is communicated with the electrolyte supplementing device and the flushing device respectively; one end of the sample electrode wire is connected with a power supply, and the other end is immersed into a to-be-extracted object. According to the device, electrolyte supplementation is continuously performed on the receiving tube through the electrolyte supplementation device, and the conductivity of a solution in the receiving tube is maintained or improved, so that the purpose of continuously amplifying the electric field intensity is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of chemical analysis, and in particular to a continuous field amplification-liquid-liquid electric extraction device and application thereof. Background Art

[0002] Electric field-assisted sample pretreatment technology, with electric field as the driving force, has greatly improved the extraction efficiency and selectivity of trace analytes, and has become the focus of field-assisted technology research. This technology has been widely used in many important fields such as food, medicine, environment and biology, and continues to demonstrate its excellent performance and wide applicability. Liquid-liquid electroextraction technology, as a membraneless electric field-assisted preparation technology, is easy to operate and easy to integrate with a variety of detection technologies. It shows multiple advantages such as fast analysis speed, high sensitivity, strong selectivity, environmental protection and energy saving, and has broad and objective application prospects.

[0003] The latest research results show that over time, the current and the migration rate of the analyte in the receiving phase of liquid-liquid electroextraction show an exponentially decreasing trend. In other words, during the electroextraction process, the electrical migration rate of the analyte from the donor phase to the receiving phase decays rapidly. If the electroextraction is not completed within a certain time window, the subsequent process will become extremely slow, which is equivalent to the "termination" of the electroextraction, seriously hindering the improvement of the electroextraction efficiency. The cause and mechanism of the rapid decay of the electroextraction rate are still unclear and have not been reported.

[0004] The existing liquid-liquid electroextraction technology is difficult to maintain a high electroextraction speed within the entire electroextraction time window, so that analytes with relatively low electrophoretic mobility are forced to "stop" (very low speed) after a certain electroextraction time before the electroextraction is completed, which seriously limits the promotion and application of the technology. Therefore, it is of great significance to break through this technical bottleneck and develop a faster and more efficient liquid-liquid electroextraction technology and device. Summary of the invention

[0005] In view of the above problems, the present invention provides a continuous field amplification-liquid-liquid electric extraction device, which continuously replenishes electrolytes to the receiving tube through an electrolyte replenishing device, maintains or improves the conductivity of the solution in the receiving tube, thereby achieving the purpose of continuously amplifying the electric field strength.

[0006] In order to achieve the above object, the present invention provides a continuous field amplification-liquid-liquid electric extraction device, comprising:

[0007] An extraction assembly, comprising an electrolyte replenishing device, a flushing device, and an electrolyte electrode wire, wherein the electrolyte replenishing device is used to contain an electrolyte solution, the flushing device is used to contain a flushing liquid, one end of the electrolyte electrode wire is used to be immersed in the electrolyte solution, and the other end of the electrolyte electrode wire is used to be grounded; and

[0008] The sample assembly includes a sample container, a receiving tube, and a sample electrode wire. The sample container is used to contain the object to be extracted. One end of the receiving tube is used to immerse the object to be extracted, and the other end of the receiving tube is respectively connected to the electrolyte replenishing device and the flushing device; one end of the sample electrode wire is used to connect to a power supply, and the other end of the sample electrode wire is used to immerse the object to be extracted.

[0009] The inventors found in the process of studying the above technical problems that in the electroextraction technology, the target object quickly migrates from the larger volume of the donor phase to the small volume of the receiving phase under the action of the electric field force, which can achieve high multiple enrichment. However, due to the small volume of the receiving phase, the amount of electrolyte it can accommodate is limited, and the electrolyte is easily exhausted quickly during the electroextraction process. At this time, the resistance of the receiving phase will increase significantly, so that the electric field is concentrated in the receiving phase rather than the donor phase, which leads to a weak electric field distribution in the donor phase, insufficient electric field force, and a sudden decrease in the migration speed of the analyte to the donor phase, which hinders or even stagnates the extraction process. Therefore, the inventors speculate: Can an appropriate amount of electrolyte be added in a suitable manner during the electroextraction process to reduce the resistance of the receiving phase, so that a higher electric field is continuously distributed in the donor phase (i.e., continuous field amplification), and maintain a higher migration speed of the analyte in this area, thereby improving the electroextraction efficiency? Therefore, the inventors propose the above-mentioned continuous field amplification-liquid-liquid electroextraction device, which continuously supplements the electrolyte to the receiving tube through the electrolyte supplement device, maintains or improves the conductivity of the solution in the receiving tube, thereby achieving the purpose of continuously amplifying the electric field strength. The device can introduce a dynamic electrolyte replenishment mechanism for the receiving phase during the electro-extraction process, effectively solving the problem of the difficulty in maintaining a stable electric field intensity in traditional liquid-liquid electro-extraction.

[0010] In one embodiment, the electrolyte replenishing device includes an electrolyte syringe and a syringe pump, and the electrolyte syringe is fixed to the syringe pump.

[0011] By precisely controlling the pumping speed of the above-mentioned injection pump, not only can the trace target be efficiently concentrated and enriched in the receiving tube, but the compression state of the analyte enrichment zone can also be flexibly controlled, thereby significantly improving the overall efficiency and accuracy of the electrical extraction, providing a more advanced and controllable solution for the extraction of trace analytes.

[0012] In one embodiment, one end of the electrolyte electrode wire is inserted into the tail of the piston rod of the electrolyte syringe and exposed at the head of the piston rod;

[0013] The flushing device comprises a flushing liquid syringe.

[0014] In one embodiment, the receiving tube is connected to the electrolyte replenishing device and the flushing device respectively through a three-way pipe.

[0015] The present invention also provides a continuous field amplification-liquid-liquid electroextraction analysis method, comprising the following steps: preparing a sample to be extracted, preparing a standard sample, using the continuous field amplification-liquid-liquid electroextraction device to perform electroextraction to obtain a sample to be tested and a standard sample, and detecting and analyzing the sample to be tested and the standard sample.

[0016] In the above analysis method, during the electro-extraction process, a high-concentration electrolyte solution is continuously introduced into the receiving phase at a low flow rate by measuring the flow, and the old solution is pushed out of the receiving phase, so as to avoid the decrease in the resistivity of the receiving phase and keep the electric field strength of the donating phase at a high level (continuous field amplification), thereby maintaining a faster migration rate of the analyte in the donating phase, further improving the speed and capacity of the electro-extraction, and achieving more efficient enrichment. The pumping conditions and the conditions of the electro-extraction system can be adapted to avoid the enriched analytes being pushed back to the donating phase, and the compression degree of the analyte enrichment zone in the receiving phase can be adjusted by regulating the supplementary pumping speed. This technology is easy to operate, low cost, and has a good enrichment effect.

[0017] In one embodiment, the sample to be tested is enriched in the receiving tube;

[0018] The electrical extraction comprises: flushing the receiving tube with a flushing liquid, and after the voltage is boosted to the electrical extraction voltage, continuously injecting the electrolyte solution into the receiving tube with an electrolyte replenishing device.

[0019] The above-mentioned continuous field amplification-liquid-liquid electroextraction device is used for electroextraction, so that an analyte-enriched zone is formed in the receiving tube. The zone is at a certain distance from the tube mouth, which can avoid the target object from reverse osmosis back to the sample tube when collecting the solution in the receiving tube. In addition, the compression state of the analyte-enriched zone can be adjusted by regulating the pumping speed of the supplementary electrolyte solution during the electroextraction process.

[0020] In one embodiment, the electrical extraction voltage is -30 to 30 kV, the electrical extraction time is 1 to 30 min, and the injection rate of the electrolyte solution is 0.1 μL / min to 50 μL / min.

[0021] Adding electrolytes to the receiving phase during the liquid-liquid electroextraction process may lead to some adverse consequences. First, in the dynamic mass transfer process of electroextraction, the electrolyte solution is pumped into the trace receiving phase, and the electrolyte solution of the receiving phase must be pumped out from the other end, which may push out the analyte just enriched in the receiving phase and return it to the receiving phase, but reduce the extraction efficiency. Secondly, supplementing the electrolyte solution to the tiny receiving phase during the dynamic electroextraction process may cause a significant change in the conductivity of the receiving phase and a sudden increase in the current, thereby overloading the power supply and interrupting the electroextraction; especially when facing the analysis of samples with complex matrices, the background current is already very high, and the risk of power overload is higher. Therefore, the inventors conducted a visual pre-experiment (under power-off conditions) on the basis of a continuous field amplification-liquid-liquid electroextraction device, and pushed the supplementary electrolyte into a 50cm micro-liter receiving tube (diameter 0.37mm). The dynamic push of a trace amount will push the target pigment back into the giving phase bottle. Considering that if a receiving tube with a larger diameter is used, a higher concentration of electrolyte solution and a faster electrolyte solution injection speed can be matched, the inventor proposes the above-mentioned pumping conditions based on the common receiving tube sizes on the market, which can prevent the analyte from being pushed out of the tube. When the speed is greater than the above-mentioned speed range value, the color in the sample tube deepens and the sample begins to be pushed out. In addition, the above-mentioned low-speed pumping conditions can avoid power overload and solve the problem of sudden current increase found during the experiment. On this basis, in combination with appropriate electrical extraction conditions, the adverse consequences that may be caused by adding electrolytes to the receiving phase during the electrical extraction process can be solved, and "continuous field amplification" and the improvement of electrical extraction efficiency can be truly realized.

[0022] In one embodiment, the electrolyte solution is injected at a rate of 1.07 μL / min to 10.20 μL / min.

[0023] In one embodiment, the electrical extraction voltage is -30 to -5 kV.

[0024] In one embodiment, the electrical extraction voltage is -18 to -5 kV.

[0025] In one embodiment, the electrical extraction time is 1 to 20 minutes.

[0026] In one embodiment, the electrolyte solution includes electrolytes, and the concentration of the electrolytes in the electrolyte solution is 0.1 to 1000 mmol / L;

[0027] The flushing solution includes electrolytes, and the concentration of the electrolytes in the flushing solution is 0.1 to 1000 mmol / L.

[0028] Considering that when selecting different types of power supplies, based on the difference in power supply load capacity, the electric extraction parameter range, reagent concentration range, and receiving tube diameter range will need to be adjusted accordingly, the concentrations of the above-mentioned electrolyte solutions and flushing solutions can be better adapted to different types of power supplies.

[0029] In one embodiment, the electrolyte solution includes electrolytes, and the concentration of the electrolytes in the electrolyte solution is 1 to 60.0 mmol / L;

[0030] The flushing solution includes electrolytes, and the concentration of the electrolytes in the flushing solution is 1 to 30 mmol / L.

[0031] In one embodiment, the concentration of the electrolyte in the electrolyte solution is 3 to 60 mmol / L.

[0032] In one embodiment, the concentration of electrolyte in the flushing solution is 2-30 mmol / L.

[0033] In one embodiment, the electrolyte includes malonic acid and / or triethylamine.

[0034] In one of the embodiments, the electrolyte solution comprises a methanol-acetonitrile solution with a volume fraction ratio of 50:50, the flushing solution comprises a methanol-acetonitrile solution with a volume fraction ratio of 50:50, and the power supply is a positive-negative switchable 0-30 kV power supply.

[0035] The present invention also provides the application of the continuous field amplification-liquid-liquid electroextraction analysis method in cosmetics testing.

[0036] The present invention also provides a method for detecting perfluoro and polyfluoroalkyl substances in cosmetics, which uses the continuous field amplification-liquid-liquid electroextraction analysis method for detection.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The continuous field amplification-liquid-liquid electric extraction device, method and application of the present invention continuously replenishes electrolytes to the receiving tube through an electrolyte replenishing device to maintain or improve the conductivity of the solution in the receiving tube, thereby achieving the purpose of continuously amplifying the electric field strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1Schematic diagram of the structure of the continuous field amplification-liquid-liquid electroextraction device in Example 1; wherein 10 is a high-voltage power supply, 20 is a precision injection pump, 30 is an electrolyte syringe, 31 is a high-concentration electrolyte solution, 40 is a flushing liquid syringe, 41 is a low-concentration organic electrolyte solution, 50 is a three-way pipe, 60 is a stainless steel electrode wire, 70 is a platinum electrode wire, 80 is a receiving tube, 90 is a sample tube, and 91 is an object to be extracted;

[0040] Figure 2 Schematic diagram of the state of the continuous field amplified electric extraction device in Example 1 during the electric extraction process; wherein 20 is a precision injection pump, 30 is an electrolyte syringe, 31 is a high-concentration electrolyte solution, 40 is a flushing liquid syringe, 41 is a low-concentration organic electrolyte solution, 70 is a platinum electrode wire, 80 is a receiving tube, 90 is a sample tube, 91 is an object to be extracted, and 92 is a target enrichment zone;

[0041] Figure 3 This is a schematic diagram of the extraction of allura red in the sample tube and the receiving tube in Example 2, wherein: Figure 3 (1) is the state of Allura Red in the sample tube before and 10 minutes after electro-extraction. Figure 3 (2) is the enrichment of the analyte zone after 10 min of allure red electroextraction. B0, B1, B2, B3, B4, B5, and B6 correspond to the supplementary pumping linear speeds of 0 mm / min, 10 mm / min, 20 mm / min, 30 mm / min, 40 mm / min, 50 mm / min, and 60 mm / min, respectively;

[0042] Figure 4 The extraction rate variation curve diagram of using different concentrations of supplementary electrolyte solutions in Example 3;

[0043] Figure 5 The extraction rate variation curve diagram using different pumping speeds in Example 3;

[0044] Figure 6 This is a curve diagram of the extraction rate change of different methyl tert-butyl ether contents in the sample bottle in Example 3. DETAILED DESCRIPTION

[0045] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0046] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element at the same time.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0048] source:

[0049] Unless otherwise specified, the reagents, materials, and equipment used in this example are all commercially available; the experimental methods are all conventional experimental methods in the art unless otherwise specified.

[0050] Example 1

[0051] A continuous field amplification-liquid-liquid electric extraction device.

[0052] 1. The structural diagram of the device is as follows Figure 1 shown.

[0053] The continuous field amplification-liquid-liquid electric extraction device comprises an extraction component and a sample component.

[0054] The extraction component includes an electrolyte replenishing device, a flushing device, and an electrolyte electrode wire.

[0055] In this embodiment, the electrolyte replenishing device is an electrolyte syringe 30 and a precision injection pump 20. The electrolyte syringe is fixed to the precision injection pump and is used to contain an electrolyte solution. In this embodiment, the electrolyte solution is a high-concentration organic electrolyte solution. The electrolyte electrode wire is a stainless steel electrode wire 60, one end of which is inserted into the piston rod of the electrolyte syringe and passes through the rubber head on the piston rod to contact the high-concentration electrolyte solution 31, and the other end is grounded. The flushing device is a flushing liquid syringe 40, which is used to contain a flushing liquid. In this embodiment, the flushing liquid is a low-concentration organic electrolyte solution 41. Before each electrical extraction, it is manually pushed to flush the receiving tube 80 and update the solution in the tube.

[0056] The sample assembly includes a sample container, a receiving tube, and a sample electrode wire.

[0057] In this embodiment, the sample container is a sample tube 90, which is used to contain the object to be extracted 91; one end of the receiving tube is connected to the electrolyte syringe and the flushing liquid syringe through a three-way tube 50, and the other end is used to immerse the object to be extracted; the sample electrode wire is a platinum electrode wire 70, one end of which is used to connect to a power supply, and the other end is used to immerse in the object to be extracted.

[0058] 2. The continuous field amplification-liquid-liquid electroextraction device is assembled according to the following steps.

[0059] 1. Insert the stainless steel electrode wire 60 into the piston rod of the electrolyte syringe 30 and pass through the rubber head on the piston rod to form a "syringe electrode" structure. One end of the stainless steel electrode wire 60 contacts the high-concentration electrolyte solution 31, and the other end is connected to the ground wire.

[0060] 2. One end of the three-way tube 50 is connected to the electrolyte syringe 30 through a Luer connector, and the other end of the three-way tube is connected to the flushing liquid syringe 40 through a Teflon tube, and the end thereof is connected to the receiving tube 80.

[0061] 3. Inject a high-concentration electrolyte solution 31 (i.e., electrolyte solution) into the electrolyte syringe 30, and then fix the electrolyte syringe 30 on the precision injection pump 20; in this embodiment, the high-concentration electrolyte solution 31 is a methanol-acetonitrile solution with a volume fraction of 50:50, which contains a certain concentration of organic electrolyte; the organic electrolyte is 30 mmol / L malonic acid and 30 mmol / L triethylamine.

[0062] 4. Inject a low-concentration organic electrolyte solution 41 (i.e., flushing liquid) into the flushing liquid syringe 40. The low-concentration organic electrolyte solution 41 is a methanol-acetonitrile solution with a volume fraction of 50:50, and the organic electrolyte is 3 mmol / L malonic acid and 3 mmol / L triethylamine. Before each electro-extraction, the flushing liquid syringe 40 is manually pushed to flush the receiving tube 80 and update the receiving phase solution in the tube.

[0063] 5. Immerse the other end of the receiving tube 80 and the platinum electrode wire 70 connected to the high-voltage power supply 10 into the sample tube 90 containing the object 91 to be extracted.

[0064] Compared with the existing liquid-liquid electroextraction technology, the continuous field amplification-liquid-liquid electroextraction device for enriching trace analytes of the present invention realizes the amplification of the electric field intensity during the electroextraction process, further improving the speed and capacity of liquid-liquid electroextraction. It is easy to operate, low in cost, and has excellent enrichment effect.

[0065] The electric extraction device starts the precision injection pump 20 during the electric extraction process, pushes the electrolyte injector 30, and performs low-speed supplementary pumping of the high-concentration electrolyte solution 31 to the receiving tube 80, so that the conductivity of the solution in the receiving tube 80 is maintained or improved, the electric field strength is continuously amplified, and the electric extraction efficiency is improved. The device can adjust the pumping speed of the high-concentration electrolyte solution by regulating the precision injection pump, thereby achieving the adjustment of the compression state of the analyte enrichment zone.

[0066] The receiving tube 80 can be made of insulating material PEEK or Teflon tube. In this embodiment, it is connected to the end of the three-way tube 50, and its length is 50 cm. The inner diameter of the PEEK tube is 0.37 mm, and the inner diameter of the Teflon tube is 0.38 mm. The sample tube 90 is a polypropylene EP tube with a capacity of 10 mL. The three-way tube is made of polypropylene, Y-shaped, 12.6 mm long, 8.6 mm wide, 1.7 mm outer diameter, and 1.0 mm inner diameter.

[0067] In this embodiment, the high voltage power supply 10 is a positive and negative switchable 0-30 kV power supply, the diameter of the stainless steel electrode wire 60 is 1 mm, and the diameter of the platinum electrode wire is 0.5 mm. The precision injection pump 20 replenishes the pumping flow rate of 1.07 μL / min to 10.20 μL / min, and the collection flow rate is 540 μL / s. The electrolyte syringe 30 fixed on the precision injection pump 20 for injecting a high concentration electrolyte solution 31 has a capacity of 10 mL, and the flushing liquid syringe 40 for injecting a low concentration electrolyte solution 41 has a capacity of 5 ml.

[0068] 3. A continuous field amplification-liquid-liquid electroextraction analysis method.

[0069] See also Figure 2 , which is a schematic diagram of the state of the electric extraction process using the continuous field amplification electric extraction device of the present invention. The method of enriching trace analytes using the electric extraction device comprises the following steps:

[0070] S1: Prepare the sample solution to be tested; weigh about 20 mg of the sample to be tested into a sample bottle; extract the sample to be tested in the sample bottle using a methanol-acetonitrile solution and methyl tert-butyl ether with a volume fraction of 50:50, and the volume ratio of the methanol-acetonitrile solution to methyl tert-butyl ether is 0.25:1-0.43:1, and the specific operation is vortex oscillation for 3 minutes, water bath ultrasound for 30 minutes, and centrifugation at 10000 rpm for 5 minutes;

[0071] S2: Prepare a series of standard sample solutions; prepare samples of known concentration by adding standard solutions to blank samples; extract the target compound in the sample using equal amounts of methanol-acetonitrile solution and methyl tert-butyl ether, with the specific operation of vortexing for 3 minutes, water bath sonication for 30 minutes, and centrifugation at 10,000 rpm for 5 minutes;

[0072] S3: Assemble the above-mentioned continuous field amplification-liquid-liquid electric extraction device, and extract the sample solution to be tested and the standard series sample solution respectively; before the electric extraction, first flush the receiving tube 80 by injecting the flushing liquid syringe 40 containing the low concentration electrolyte solution, and fill it with the low concentration electrolyte solution 41, such as Figure 2 As shown in state a.

[0073] S4: Adjust the voltage range of the high voltage power supply 10 to -18 to -5 kV (i.e., the electrical extraction voltage). When performing electrical extraction, immerse the receiving tube 80 and the platinum electrode wire 70 into the sample solution. At this time, the sample solution in the initial state is as follows: Figure 2 Turn on the power supply, wait for 10 to 20 seconds after the high-voltage power supply is boosted, and then immediately turn on the precision injection pump 20 to continuously push the electrolyte syringe 30 that injects the high-concentration electrolyte solution. The pumping speed is 1.07 μL / min to 10.20 μL / min (i.e., the speed of electrolyte solution injection). At this time, the sample solution is as follows Figure 2 As shown in state c, the duration of electro-extraction is 1 to 20 minutes (i.e., electro-extraction time). When the electro-extraction is finished, the power supply and the precision injection pump are turned off at the same time. When the extraction is finished, the sample solution is as follows Figure 2 As shown in state d, the solution in the sample tube changes from the initial red solution to a colorless transparent solution, and a target enrichment zone 92 is formed, showing the color of the target.

[0074] S5: After the extraction is completed, set the precision syringe pump injection speed to 540μL / min. Figure 2 As shown in state e, the precision injection pump is started, and the analysis and detection are directly performed online or 90 μL of the sample injection liquid to be tested or the standard injection liquid is collected in the receiving tube for analysis and detection.

[0075] S6: Compare and analyze the liquid chromatogram of the enriched sample solution with the liquid chromatograms or mass spectra of a series of enriched standard solutions of known concentrations. During the comparison process, if the retention time of a specific component in the liquid chromatogram of the enriched standard solution coincides with the retention time of a characteristic peak in the sample solution, the characteristic peak will be regarded as a characteristic mark produced by the same substance as the corresponding component in the standard solution. Based on the peak area of ​​this characteristic mark, the content of the target compound in the sample can be accurately calculated using the established accompanying standard curve.

[0076] Example 2

[0077] 1. The instruments used in this example include the continuous field amplification-liquid-liquid electroextraction device and micropipette for enriching trace analytes described in Example 1. The reagents used include: methanol, acetonitrile, triethylamine (chromatographic grade); malonic acid, methyl tert-butyl ether (analytical grade).

[0078] The conductive liquid of the electric extraction device is prepared in advance. During the electric extraction process, different concentrations of conductive liquid are used to pump and supplement the solution in the receiving tube. After comparing the extraction results, a methanol-acetonitrile solution containing 30.0mmol / L malonic acid and triethylamine is selected as the supplementary pumping conductive liquid. With the conductive liquid of this composition ratio, the allure red substance in the sample bottle is completely extracted after electric extraction, and the solution in the sample bottle is clear and transparent. The steps for preparing the conductive liquid are: weigh 0.312g malonic acid with a 1 / 10000 electronic balance and put it into a 100mL volumetric flask, add a small amount of methanol-acetonitrile solution with a volume fraction of 50:50 to dissolve it, add 420μL triethylamine, and dilute to the scale with a methanol-acetonitrile solution with a volume fraction of 50:50, shake and set aside. A methanol-acetonitrile solution containing 3.0mmol / L malonic acid and 3.0mmol / L triethylamine was selected as the receiving phase solution. The low-concentration conductive liquid in the receiving tube was rinsed and updated before the electro-extraction. The conductive liquid with this composition ratio can avoid the problem of bubbles caused by Joule heat generated by current overload during the electro-extraction process. The steps for preparing the conductive liquid are: weigh 0.0312g malonic acid with a 1 / 10000 electronic balance and put it into a 100mL volumetric flask, add a small amount of methanol-acetonitrile solution with a volume fraction of 50:50 to dissolve it, add 42μL triethylamine, and dilute to the scale with a methanol-acetonitrile solution with a volume fraction of 50:50, shake well and set aside.

[0079] 2. Samples to be tested in this embodiment: methyl tert-butyl ether suspected of being contaminated by allura red;

[0080] Standard: Allura Red, analytical grade, purchased from Shanghai MacLean Biochemical Technology Co., Ltd., batch number CAS: 25956-17-6. Weigh 5 mg of Allura Red into a 10 mL volumetric flask, dilute to the mark with a 50:50 volume fraction of methanol and acetonitrile solution, and shake to prepare a 500 μg / mL Allura Red standard solution.

[0081] The electro-extraction and enrichment of allura red in methyl tert-butyl ether by using the continuous field amplification-liquid-liquid electro-extraction device for enriching trace analytes described in Example 1 comprises the following steps:

[0082] 1. Prepare the sample to be tested.

[0083] Assemble the electric extraction device. Take 2.0 mL of methyl tert-butyl ether to be tested and 1.0 mL of a 50:50 volume fraction methanol-acetonitrile solution and add them into the sample tube, shake well to prepare the sample solution to be tested.

[0084] 2. Set the electroextraction parameters.

[0085] A transparent Teflon tube was used as a receiving tube to observe the enrichment zone of the analyte. Before the electro-extraction, a syringe with a low-concentration conductive solution (malonic acid: triethylamine = 3.0mmol / L: 3.0mmol / L) was manually injected to update the solution in the receiving tube. The high-voltage power supply parameter was set to -15Kv. When the electro-extraction started, the platinum electrode wire and the receiving tube of the electro-extraction device were immersed in the sample solution to be tested. The power was turned on. After 10S of voltage increase, the precision injection pump was started and a syringe with a high-concentration conductive solution (malonic acid: triethylamine was 30.0mmol / L: 30.0mmol / L) was injected to replenish the electrolyte solution in the receiving tube. After 10 minutes of electro-extraction, the high-voltage power supply and the precision injection pump were turned off at the same time. The state of the sample tube and the receiving tube before and after the electro-extraction was photographed with a mobile phone. The setting parameters of the precision syringe pump are: 1.13μL / min to 6.80μL / min, which is converted into a supplementary pumping linear speed of 10mm / min, 20mm / min, 30mm / min, 40mm / min, 50mm / min, and 60mm / min in the receiving tube.

[0086] 3. Analysis of electrical extraction results:

[0087] The red color remaining in the sample tube after electro-extraction was used to evaluate the extraction of allura red from MTBE; the red color enrichment in the receiving tube was used to evaluate the zone compression.

[0088] According to the analysis of the remaining color in the sample bottle, when the precision syringe pump was set to supplement the injection speed of 2.27 μL / min to 5.67 μL / min (corresponding to the supplementary pump linear speed of 20 mm / min to 50 mm / min in the receiving tube), the allura red was well extracted after 10 minutes of electro-extraction, the solution in the sample tube was transparent, and the target was enriched in the receiving tube. Figure 3 -(1). After analyzing the enrichment of allura red in the receiving tube, in this embodiment, the sample to be tested is set to supplement the injection speed of the precision injection pump at 1.13μL / min to 6.80μL / min (corresponding to the supplementary injection linear speed of 10mm / min to 60mm / min in the receiving tube). As the supplementary injection speed increases, the analyte zone is gradually compressed. See details. Figure 3 -(2), among which, although the target enrichment zone of B0 (corresponding to the supplementary pump injection linear velocity of 0 mm / min) appears red, Figure 3In (1), the test tube without additional pumping of "10 minutes after electroextraction" (i.e., the second test tube from left to right) shows that the 10-minute electroextraction cannot complete the exhaustion extraction without additional pumping of electrolyte solution, and there is still residual color in the solution in the test tube after electroextraction. Under the same electroextraction conditions, the electrolyte solution is supplemented by low-speed pumping. Figure 3 (1) The residual color of the solution in the test tube became significantly lighter, or even colorless, indicating that depletion extraction was achieved, reflecting the continuous field amplification effect.

[0089] Example 3

[0090] Continuous field amplified liquid-liquid electroextraction method was used to enrich per- and polyfluoroalkyl substances in cosmetics.

[0091] The instruments used in this example include the liquid-liquid electroextraction device for continuous field amplification enrichment of trace analytes described in Example 1; 1 / 10000 electronic balance; micropipette; Vortex-Genie adjustable vortex mixer; CT15RT desktop centrifuge; LC-20A high performance liquid chromatograph and 4000Q TRAP triple quadrupole mass spectrometer; Accucore C18 chromatographic column (100×4.6 mm, 2.6 μm, Thermo Fisher Scientific). The reagents used include: methanol, acetonitrile, triethylamine, methyl tert-butyl ether (chromatographic grade); ammonium acetate, malonic acid (analytical grade).

[0092] A high concentration of conductive liquid was pre-configured and injected into a syringe fixed on a precision injection pump. The concentration of electrolyte malonic acid and triethylamine was 1:1, and the concentrations tried were: 3.0mmol / L, 6.0mmol / L 10.0mmol / L, 30.0mmol / L, 60.0mmol / L. Figure 4(Data see Table 1) Different supplementary electrolyte concentrations - extraction of perfluorinated and polyfluoroalkyl substances in sunscreens show that the extraction rate of perfluorinated and polyfluoroalkyl substances in sunscreens is higher when the concentrations of malonic acid and triethylamine are 30.0mmol / L and 60.0mmol / L, and the methanol-acetonitrile solution containing malonic acid and triethylamine at concentrations of 30.0mmol / L and 30.0mmol / L is selected as the optimal high-concentration conductive liquid. The steps for preparing the conductive liquid are: weigh 0.312g malonic acid with a 1 / 10000 electronic balance and put it into a 100mLml volumetric flask, add a small amount of methanol-acetonitrile solution with a volume fraction of 50:50 to dissolve, add 420μL triethylamine, dilute to the scale with a methanol-acetonitrile solution with a volume fraction of 50:50, and shake well for use. The low-concentration conductivity liquid in the receiving tube is a methanol-acetonitrile solution containing 3.0 mmol / L malonic acid and 3.0 mmol / L triethylamine. The steps for preparing the conductivity liquid are as follows: use a 1 / 10000 electronic balance to weigh 0.0312 g of malonic acid and put it into a 100 mL volumetric flask, add a small amount of 50:50 volume fraction methanol-acetonitrile solution to dissolve it, add 42 μL of triethylamine, and dilute to the scale line with 50:50 volume fraction methanol-acetonitrile solution, shake well and set aside.

[0093] Table 1. Electroextraction recovery rate (%) of different supplementary electroconductive solution concentrations (n=3)

[0094]

[0095] Note: When optimizing the concentration of the supplementary conductivity solution, 2.0 mL of methyl tert-butyl ether and 1.0 mL of a 50:50 methanol-acetonitrile solution were used to extract the sunscreen, and the supplementary pumping linear speed was 20 mm / min.

[0096] Select the high concentration conductivity liquid replenishment pump speed, refer to Figure 5 (For specific data, please see Table 2). As can be seen from the figure, the extraction effect is better when the appropriate range of the precision syringe pump supplementary pumping speed is 2.15μL / min to 4.30μL / min, and the corresponding supplementary pumping linear speed in the receiving tube is 20 mm / min to 40 mm / min. The optimal high-concentration conductivity liquid supplementary pumping linear speed is selected to be 20 mm / min.

[0097] Table 2. Electroextraction recovery rate at different supplementary pumping speeds (%) (n=3)

[0098]

[0099]

[0100] For the selected ratio of methanol, acetonitrile and methyl tert-butyl ether, please refer to Figure 6(For specific data, please see Table 3). As can be seen from the figure, when the ratio of methanol to acetonitrile and methyl tert-butyl ether is 0.25:1 to 0.43:1, the extraction effect is very good, and the corresponding methyl tert-butyl ether content in the figure is 70% to 80%. The selected methyl tert-butyl ether content is 73.3%, that is, the donor phase contains 2.2 ml of methyl tert-butyl ether and 0.8 ml of methanol to acetonitrile as the optimal donor phase.

[0101] Table 3. Electroextraction recovery of different methyl tert-butyl ether contents (%) (n=3)

[0102]

[0103] The cosmetic samples to be tested in this embodiment are:

[0104] Cosmetic samples to be tested: cosmetics suspected of being contaminated by perfluorinated and polyfluorinated alkyl substances, including sunscreen, lotion, foundation, lipstick, essential oil, eye shadow, and mascara.

[0105] Blank cosmetic samples: cosmetics that have been tested to contain no target perfluorinated and polyfluoroalkyl substances, including sunscreen, lotion, foundation, lipstick, essential oil, eye shadow, and mascara.

[0106] Standards: Perfluorobutyric acid (PFBA), Perfluoropentanoic acid (PFPeA), Perfluorohexanoic acid (PFHxA), Perfluoroheptanoic acid (PFHpA), Perfluorooctanoic acid (PFOA), Perfluorononanoic acid (PFNA), Perfluorodecanoic acid (PFDA), Perfluoroundecanoic acid (PFUdA), Perfluorododecanoic acid (PFDoA), Perfluorotridecanoic acid (PFTrDA), Perfluorotetradecanoic acid (PFTeDA), Perfluorohexadecanoic acid (PFHxDA), Perfluorooctadecanoic acid (PFOcDA), Perfluorobutane sulfonate (PFBS), perfluorohexane sulfonate (PFHxS) and perfluorooctane sulfonate (PFOS) were purchased from Amp Labs Ltd. Potassium 9-chlorohexafluoro-3-oxononane-1-sulfonate (9-Cl-SA), potassium 11-chloroeicosine-3-oxonadecane-1-sulfonate (11-Cl-SA), and 4,8-dioxa-3-hydro-perfluorononanoic acid (ADONA) were purchased from Wellington Laboratories, Canada; hexafluoropropylene oxide dimer acid (GenX) was purchased from AccuStandard, USA.

[0107] The method of enriching perfluoroalkyl and polyfluoroalkyl substances in cosmetics by using the continuous field amplification-liquid-liquid electroextraction device for enriching trace analytes described in Example 1 comprises the following steps:

[0108] (1) Prepare the sample injection solution to be tested:

[0109] Assemble the electroextraction device. Use a 1 / 10000 electronic balance to weigh 20 mg of the cosmetic sample to be tested into a 10 mL EP tube, add 2.2 mL of methyl tert-butyl ether and 0.8 mL of a 50:50 volume fraction of methanol and acetonitrile solution, vortex for 3 minutes, and centrifuge at 10000 rpm for 5 minutes after water bath ultrasound for 30 minutes to obtain the sample solution to be tested. Set the high-voltage power supply voltage to -12 kV, and the precision injection pump injection speed to 2.15 μL / min (corresponding to the conductivity liquid replenishment pump line speed in the receiving tube of 20 mm / min). Before electroextraction, push the syringe with a low concentration conductivity liquid (malonic acid: triethylamine is 3.0 mmol / L: 3.0 mmol / L) to update the solution in the receiving tube. Immerse the platinum electrode wire and receiving tube of the electric extraction device into the sample solution to be tested, turn on the power, wait for 20S to complete the pressure rise, start the precision injection pump, push the syringe injected with high-concentration conductivity liquid (malonic acid: triethylamine is 30.0mmol / L: 30.0mmol / L), and start the electric extraction. Turn off the power and precision injection pump after 8.0min, set the precision injection pump injection speed parameter to 540μL / min, and collect 90μL of the sample injection liquid to be tested in the receiving tube by pushing the injection pump for 10S.

[0110] (2) Preparation of standard injection solution:

[0111] Assemble the electric extraction device. Use a 1 / 10000 electronic balance to weigh the blank cosmetic sample in a 10mL EP tube, add 20 kinds of perfluorinated and polyfluorinated alkyl substances standard solutions so that the spiked concentration of the blank cosmetic sample is: 1ng·g -1 , 10ng·g -1 , 20ng·g -1 , 50ng·g -1 , 100ng·g -1 , 200ng·g -1 , 300ng·g -1. 2.2 mL of methyl tert-butyl ether and 0.8 mL of a 50:50 volume fraction of methanol and acetonitrile solution were added successively, vortexed for 3 min, and then centrifuged at 10000 rpm for 5 min after water bath ultrasound for 30 min to obtain the sample solution to be tested. Before electro-extraction, the high voltage power supply voltage was set to -12 kV, and the precision injection pump pumping speed parameter was set to 2.15 μL / min (corresponding to the supplementary pumping linear speed in the receiving tube of 20 mm / min). Before electro-extraction, the low-concentration conductive liquid syringe was injected to update the solution in the receiving tube, and then the platinum electrode wire and the receiving tube of the electro-extraction device were immersed in the sample solution to be tested, the power was turned on, and after the 20S boost was completed, the precision injection pump was turned on to start electro-extraction. After 8.0 min, the power supply and the precision injection pump were turned off, and the precision injection pump pumping speed parameter was set to 540 μL / min. By pushing the injection pump for 10S, 90 μL of solution in the receiving tube was collected to obtain the series of concentration standard injection liquids.

[0112] (3) Liquid chromatography-mass spectrometry detection:

[0113] The mobile phase is composed of methanol and 5mmol / L ammonium acetate aqueous solution, the flow rate is 0.8mL / min, the injection volume is 25μL, and the gradient elution mode is adopted. The initial proportion of the aqueous phase is 98%, which decreases to 2% within 6.5min, and then the proportion is maintained for 3.5min, and then it rises to 98% within 0.3min, and then it is maintained for 3.7min for equilibrium. The aqueous phase (5mmol / L ammonium acetate aqueous solution) is prepared by the following method: 0.3854g of ammonium acetate is weighed with a 1 / 10000 electronic balance and put into a 1000mL volumetric flask, and the volume is adjusted to the scale line, and then filtered and ultrasonically degassed for use.

[0114] Mass spectrometry detection conditions: negative ion MRM mode. Curtain gas: 15.0; collision gas: medium; ionization voltage: -4200V; nebulization temperature: 650℃; nebulization gas: 55.0; auxiliary gas: 60.0; inlet voltage: -10.0V; outlet voltage: -15V. The chromatographic retention time, parent ion, daughter ion, declustering voltage, and collision energy of the target are shown in Table 4:

[0115] Table 4. Chromatographic retention time, parent ion, daughter ion, declustering voltage, and collision energy parameters of the target compound

[0116]

[0117] a. For quantitative analysis

[0118] (4) Detection data processing:

[0119] After the system is balanced, the sample solution to be tested and a series of concentrations of standard solution are injected separately.

[0120] By inputting the spiked concentration of each blank cosmetic into the software, the peak area-concentration standard curve equation can be obtained, and the software calculates the results of each spiked concentration. The effectiveness and accuracy of the method for the detection of perfluorinated and polyfluoroalkyl substances are demonstrated. The detection limit, quantitative limit, accuracy and precision of each target are evaluated according to the ICH (The International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use) Q2 analytical method validation guidelines. First, the analytical method was established using sunscreen samples, using 3 times the signal-to-noise ratio as the sample detection limit and 30 times the signal-to-noise ratio as the quantitative limit. The detection limit, quantitative limit, linear range and fitting coefficient are shown in Table 5; the accuracy and precision are evaluated by calculating the intra-day and inter-day recovery and relative standard deviation (RSD), where the inter-day difference is obtained by measuring five parallel samples of three concentrations on the same day, and the intra-day difference is obtained by measuring three parallel samples of three concentrations every day for a total of five days. Secondly, the methodological verification of the inter-day difference and intra-day difference of two concentrations of other cosmetic samples was carried out. In summary, the accuracy and precision data of sunscreen and other cosmetic samples are shown in Tables 6 and 7, respectively.

[0121] Table 5. Detection limit, quantification limit, linear range and fitting coefficient of electroextraction of per- and polyfluoroalkyl substances

[0122]

[0123] Table 6. Accuracy and precision data of electro-extraction of per- and polyfluoroalkyl substances in sunscreen

[0124]

[0125]

[0126] Table 7. Accuracy and precision data of electroextraction of per- and polyfluoroalkyl substances in other cosmetics

[0127]

[0128]

[0129]

[0130] a. Recovery rate

[0131] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0132] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A continuous field amplification-liquid-liquid electroextraction device, characterized in that: include: An extraction assembly, comprising an electrolyte replenishing device, a flushing device, and an electrolyte electrode wire, wherein the electrolyte replenishing device is used to contain an electrolyte solution, the flushing device is used to contain a flushing liquid, one end of the electrolyte electrode wire is used to be immersed in the electrolyte solution, and the other end of the electrolyte electrode wire is used to be grounded; and The sample assembly includes a sample container, a receiving tube, and a sample electrode wire. The sample container is used to contain the object to be extracted. One end of the receiving tube is used to immerse the object to be extracted, and the other end of the receiving tube is respectively connected to the electrolyte replenishing device and the flushing device; one end of the sample electrode wire is used to connect to a power supply, and the other end of the sample electrode wire is used to immerse the object to be extracted.

2. The continuous field amplification-liquid-liquid electric extraction device according to claim 1, characterized in that: The electrolyte replenishing device comprises an electrolyte syringe and a syringe pump, and the electrolyte syringe is fixed to the syringe pump.

3. The continuous field amplification-liquid-liquid electric extraction device according to claim 2, characterized in that: One end of the electrolyte electrode wire is inserted into the tail of the piston rod of the electrolyte syringe and exposed at the head of the piston rod; The flushing device comprises a flushing liquid syringe.

4. The continuous field amplification-liquid-liquid electroextraction device according to claim 1, characterized in that: The receiving tube is connected to the electrolyte replenishing device and the flushing device respectively through a three-way tube.

5. A continuous field amplification-liquid-liquid electroextraction analysis method, characterized in that: The following steps are involved: Prepare samples to be extracted and standard products, use the continuous field amplification-liquid-liquid electric extraction device described in any one of claims 1 to 4 to perform electric extraction to obtain samples to be tested and standard samples, and detect and analyze the samples to be tested and standard samples.

6. The continuous field amplification-liquid-liquid electroextraction analysis method according to claim 5, characterized in that: The sample to be tested is enriched in the receiving tube; The electrical extraction comprises: flushing the receiving tube with a flushing liquid, and after the voltage is boosted to the electrical extraction voltage, continuously injecting the electrolyte solution into the receiving tube with an electrolyte replenishing device.

7. The continuous field amplification-liquid-liquid electroextraction analysis method according to claim 6, characterized in that: The electric extraction voltage is -30 to 30 kV, the electric extraction time is 1 to 30 min, and the injection speed of the electrolyte solution is 0.1 μL / min to 50 μL / min.

8. The continuous field amplification-liquid-liquid electroextraction analysis method according to any one of claims 5 to 7, characterized in that: The electrolyte solution includes electrolytes, and the concentration of the electrolytes in the electrolyte solution is 0.1 to 1000 mmol / L; The flushing solution includes electrolytes, and the concentration of the electrolytes in the flushing solution is 0.1 to 1000 mmol / L.

9. Application of the continuous field amplification-liquid-liquid electroextraction analysis method according to any one of claims 5 to 8 in cosmetics testing.

10. A method for detecting perfluoroalkyl and polyfluoroalkyl substances in cosmetics, characterized in that: The detection is carried out using the continuous field amplification-liquid-liquid electroextraction analysis method described in any one of claims 5 to 8.

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